Battery life is arguably becoming a laptop’s most important metric. Processor speed is confusing – different architectures have different performance at different clock speeds. Discrete graphics is even worse. But the battery? More is better! Everyone knows that. And manufacturers have latched on to it as an important marketing tool.
This has led to amazing claims. Six, seven, eight hours or more – some modern laptops pose with endurance numbers rivaling tablets. There’s just one problem. No one checks to make sure advertising and reality match. Manufacturers can claim anything they’d like.
We’re going to take manufacturer claims to task by examining 10 recently released laptops and comparing their claimed battery endurance with the results we received during our reviews. Let’s see if these laptops can back up their boasts.
We wanted to have a well-rounded list of laptops for this comparison, so we’ve picked ten recently reviewed models. Some are Ultrabooks, some are desktop replacements, and some are luxury portables. Here’s the list of competitors and the battery life listed by the manufacturer on its website. Not every laptop we’ve reviewed is marketed alongside a battery life number, so we’ve picked laptops that claim a definite number. The text below is quoted from manufacturer marketing or spec sheets.
- ASUS UX31 – 7 hours or more
- ASUS U36JC – Up to 10 hours
- HP Folio 13 – Up to 9.5 hours
- HP dm1z – Up to 10 hours
- Lenovo IdeaPad U400 – Up to 4 hours
- Lenovo ThinkPad T420 – Up to 5.5 hours
- Sony Vaio SE 15.5” – Up to 6 hours
- Sony Vaio Z – Up to 7 hours and 15 minutes
- Toshiba Portege Z835 – Up to 8 hours of “non-stop browsing, emailing, doing and enjoying”
- Toshiba Satellite P755 – Up to 5.7 Hours
If we average all of these numbers we come to a total average battery life of 7.3 hours (rounding up slightly). That’s quite robust. Many of these laptops are portable because manufacturers usually send us high-end models for review rather than stripped-down desktop replacements, but even so, seven hours is excellent.
Now let’s see if these claims are met.
Real battery life
For the purposes of this comparison we are going to be using the numbers generated by our Battery Eater Reader’s Test benchmark. This is not a strenuous workload. It opens a document and scrolls through it endlessly. We leave Wi-Fi on and display brightness at 70 percent. We also engage the most aggressive power-saving mode available. These conditions should result in solid battery life results.
In the table below we’ve compiled our results and the difference, both for each laptop and for all laptops as a whole. Let’s take a look.
What we find most interesting about these results is how well they break down by manufacturer. The Asus laptops are off by exactly 10%. The HP laptops are off by 16 percent and 15 percent. The Sony laptops are off by exactly 15 percent. Only Toshiba and Lenovo show significant variance, but both are consistent in the direction of their results – the Toshiba laptops underperformed and the Lenovo laptops beat their estimates.
Lenovo’s IdeaPad U400 is the real surprise thanks to an insanely low manufacturer claim of four hours. We applaud Lenovo for apparently being more realistic about real-world results, but at the same time, Lenovo’s laptops offered shorter run times than the competition.
Interpreting the results
The overall variance is negative 11 percent, but if we exclude Lenovo, the difference increases to negative 14 percent.
Does this mean that you should expect at least 14 percent less than what is claimed? Yes, it does. Though these 10 laptops are obviously only a small portion of the market, in our experience it is rare for any laptop to meet its claimed maximum life under any conditions that involve active use of the laptop.
Even expecting 14 percent less than what is claimed may be hopeful. The benchmark reference in this article is the least demanding of the two we use. Placing a heavy load on the processor is going to eat through the battery even more quickly. Playing a game, for example, can cut battery life below 50 percent of what is claimed.
Manufacturers account for this by using the words “up to” in their advertising. With that said, some manufactures walk a finer line than others. ASUS claims the UX31 can achieve 7 hours or more on the specifications page of its website. Toshiba claims that Z835 offers up to eight hours of “non-stop browsing, emailing, doing and enjoying.” These claims are simply incorrect.
Though it’s possible that a laptop will meet or exceed its claim, you shouldn’t expect it. Instead, you should expect a laptop to come in below its maximum by at least 14 percent and – more realistically – around 25 percent.
A silver lining
All of this sounds a bit doom-and-gloom, so let’s end on a high note. While we do find that laptops fail to meet their quoted endurance in our battery life benchmarks, there has been an upward trend in real-world battery life.
Five years ago you’d be lucky to achieve three hours with a basic desktop replacement, but the worst battery life we recorded among the systems in this comparison was a tad over five hours. The average buy should find this to be more than adequate. Even if claims are not being met, real-world battery results do not fail to impress.